Mechanical unloading device for compressors



May 26, 1925 1,538,937

- c. M. HOLLEY ET AL MECHANICAL UNLOADING DEVICE FOR COMPRESSORS Original Fil'd'ne'c. 24,1919 2 Sheets-Sheet 1 May 26, 1925.

' C. M. HOLLEY ET AL MECHANICAL UNLOADING DEVICE FOR cbMPREssoRs 2 sheets-sheet 2 Original Filed Db. 24, 1919 'HIIII Illl 'IIH 9 m 0 a 6 W, J i m ,6 1| 8 6 2 a 2 Zari P 00mm! the- United State Patented May 26, 1925. 1

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Application '11.; December 241 1919, Serial Hort 47 1184. Renewed A ril e, 1025.

To allwhom it may conaem:.

Be it known that we, CLARENCE M. HOLLEY and EARL P.' OSWALD, citizens of I s residing at Detroit, county of- Wayne, tate of Michi an, haye invented a certain new and useful mprovement in Mechanical Unloading Devices for Compressors, and declare the following to be a full, cleargand exact description of the same, such as will enable others skilled in the. art to' which it pertains to make and use the same, reference being had to the accompan in drawin s which form a part of y g s, p

1 this specification.

This invention relates to automatic load control devices for compressors, the object beingto provide a .mechanical device for automatically unloading a compressor for 20 air'orother fluids -when idle to relieve the motor ofthe load during" the starting period; Compressors for a refrigerant used in artificial refrigerating systems are usualoperated-by an electric motor and usually 1 tlie compressors remain under the load of the high pressure --side of 'the circulating g system when not in operation and thus a motor is required of greater capacity and current consumption to start under the-load than is required-when operating at full speed. lhe object of this invention is to provide mechanism'to automatically release the compressors of 'the load in order that a motor of comparatively small starting torque and small current consum tion may be utilized, as a moton-ivhen un er full speed'can assume a load which is in excess of its capacity during the starting interval. The principal feature; of this invention is involved in the use of centrifugally operated mechanical applicance adapted to open the valves of the compressor when operated be low a predetermined'speed and thus permit the motor to start and operate up to the time of attaining the predetermined speed without assumption of full load of ,the compressor. A further object of this invention ls-to provide a motor and compressor outfit for an artificial refrigerating system in which the motor and compressor unit is enclosed within'a part of the circulating system preferably on the low pressure s1de thereof and to provide in conjunction therewith mechanism actuated by centrifugal force to hold the intake valves open and.

permitthe pistons 'of the compressor to operate without transference" of the fluid fromthe low to the high pressure sides of the systems until a certain predetermined speed .is attained whereupon the intake 1 valves are permitted toclose and operate in the normal .manner. These and other obectsand the'several novel features of the invention are hereinafter more fully described, and claimed, and the preferred form showmg the compressor and motor unit in a portion of the circulating system of an artificial refrigerating apparatus.

Fig. 2 is a section taken on line 2-2 of Fig. 1 showing the compressorunit in plan view.

Fig. 3 is an enlarged section through the head of the motor showing the inlet valves and portion of the cylinders.

7 hi 4: is an elevation partly in section showing the control apparatus in position assumed to open the inlet valve of the vcompressor when the motor is idle.

Fig. 5 is a similar view showing the control apparatus in the position assumed when under operation releasing the valve to its normal operation.

lhe electric motor 1 and the compressor or pump unit'2 are enclosed within a casing 3 into which the low pressure line 4: of'an artificial refrigerating system opens and from which the high pressure line 5 leads, the high pressure line being directly'connected by a pipe 6 with said discharge line. This construction and relationship of the casing or chamber 3 with an artificial refrigerating system and the function thereof is set forth and described in our pending inders 11 and '12 having reciprocable' pis tions thereinconneoted with the crank shaft.- in the usual manner of compressors. Each compressor is provided with an intake valve 13 and an exhaust valve 14, both of which are to be understood-as being springsseat d -der pressure to the hig valves ofthe usual type. The inlet valves both open to a chamber 15 which s open, by means of the aperture 16, to the mterior of the casing 3 from whichthe com res slplfs' receive the fluid to be compresse check valves 14 each open to a chamber 17 individual thereto which are to be understood as connected together and discharging into the conduit 6 leading to the discharge line.

In operation of these compressors the 'refrigerant fluid is drawn through the orifice 16 and past the valves 13- into the cylinders of the compressor which alternately draw fluid thereinto and dischar e therefrom unpressure line. Heretofore, to operate these pistons in the compressors, the pistons on the initial upstroke must compress the fluid in the cylinders to a degree slightly in excess of the pressure of the high pressure line in order to discharge the same thereinto and with an electric motor operating the pistons this initial load requires a. motor of greater capacity than is required after the motor has attained full speed. Thus, generally, a

motor of excessive current consumption and of comparatively high first cost has necessarily been heretofore utilized. This invention seeks to provide an automatic mechanical device for opening the intake valves 13 when the compressor is at rest or operating below a certain predetermined rate of speed. This is accomplished bymeans of a lever 18 pivoted at 19 adjacent each intake valve and provided with a rounded end 20 adapted to engage the upper end of the valve stem; therebeing a lever for each intake valve of the several compressors that may be utilized. This lever at a point remote from the pivot point has a plunger 21 connected thereto by a pin 90 extending through a slot 91 in the lever. The plunge-r extends through a housing 22 in which it is movable longitudinally. This housing is mounted in a bushing 23 supported in a boss on the casting 24 forming part of the head of the compressor in the construction here shown. The housing 22 has provided on the lower end thereof a gear 25 with which meshes a gear 46 secured to the motor shaft 7. Rotation of the motor shaft rotates the gear 25 and housing 22 about the plunger 21. The gear 25 has a pair of lugs .26 and 27 depending from the lower side thereof to which are lpivoted the plunger operating dogs 26 eac similar in character and eachhaving an end 29 adapted to engage the lower end of the plunger 21 as will be understood from Fig. 4. These dogs 28 are weighted at the lower end and are connected together by a spring 30 tending to,. draw them to the position shown in Fig. 4

the pistons may operate in the cylin meats? shaft 7 is idle or operating at a s eedinsufficient to cause the weighted 0 s to be thrown outward by centrifugal Force exceeding the tension of the spring 30. Thus, when the motor is idle or while it is starting and up to the point where the centrifugal action is not sufficient to cause the do to be thrown outward at the weighted end: as stated, the inlet valves are held 0 en and d ers,. the only load placed u on the motor being the friction caused by t e movement of the iston in the cylinders. With the inlet -va ves held open, the fluid is drawn into the c linders and moved'outward through the 1ntake valves only and thus an electric motor of small capacity and small startingtorque may be utilized with the control mechanism described.

Upon the motor shaft 7 attaining sufficient ing in their designed manner. Immediately upon cessation of operation of the motor and its speed being reduced below that sufficient to cause actuation ofthe weighted dogs as described. the spring 30 draws the weighted ends of-the dogs together and raising the ends 29 against the plunger 21 and which, by-reason of the leverage of the lever 18, opens the valves holding the same open until the motor is again operated.

The mechanism is simple in the extreme and while we have shown two compressors, one or any number of compressors may be employed as may be desired. Preferably, each intake valve should be provided with centrifugal valve operating apparatus tending to open the same during the idle period of the motor as heretofore stated.

We are aware of other mechanism in which the intake valves are opened upon current being applied to the motor to start the same. The herein described mechanism differs from such former type of mechanism as these valves 13 are opened immediately u on cessation of operation of the motor s aft. This is preferable for the reason that valves remaining closed for a long period are apt to stick due to the fact that the intake valves are open to the low pressure side of the refrigerating system and nger is I therefore subject to comparatively low thus are opened prior .to there being possibility of their freezing to the seat.

7 Having thus full described our invention, what we claim an desire to secure by Letters Patent of the United States is- 1. In a fluid pressure system, the combination with a compressor having a high and a low ressure line, of a casing or chamber form ng part of the low pressure line and enclosing the compressor, an inlet valve of the compressoropening to the chamber, a discharge valve for the compressor opening directly to the high pressure line, a motor in the chamber, and a centrifugally operated meanswithin the chamber driven by the motor and acting to hold the inlet valve open to the chamber until the motor has attained a predetermined speed of operation.

2. In a fluid pressure system, the combination with a compressor having a high and a low pressure line, of a casing or chamber forming part of the low pressure line-and enclosin the compressor, said compressor comprising a pair of cylinders operating in alternate relation, a motor in the chamber having a shaft occupying a vertical position adapted to operate the compressors, each compressor having a spring closed inlet valve opening to the chamber and a discharge valve opening directly to the high pressure line, a pivoted lever for each inlet valve, one end of each lever engaging the stem of the inlet valve, weighted levers tending when idle to actuate the lever to depress the inlet valve stem and 0 en said valve, a

gear for each pair of weighted levers by which the same may be rotated, a spring tending to draw the weighted levers together and hold the inlet valve open, and a gear on the motor shaft meshin with both of said first named gears w ereby the weighted levers are rotated through. rotation of the lever shaft and the valves released upon attainment of the predetermined motor speed. V

3. In a fluid pressure system, the .combination with a compressor having a high and low ressure line, of .a casing or chamber forming a part of the lower pressureline and enclosing the compressor, a motor in "the chamber for operating the compressor, a

spring closed inlet valve for the compressor opening to the chamber, a discharge valve for the compressor opening directly to the high pressure, a pivoted lever having an end engaging the stem of the inlet valve, a centrifugal y lever to release the inlet valveto its spring, said centrifugal means bein directly conoperated means for actuating the nected with the motor sha t whereby the speed of themotor directly controls the release of the inlet valve.

4. A mechanical unloading device for fluid compressors comprising the combinawith a compressor having a spring closed inlet valve, an electric motor for operating the compressor, of a lever pivotally mounted upon the compressor head having one end engaging the valve stem, a plunger or rod at the opposite end of the lever, a centrally a ertured housing in which the rod is mova le longitudinal y, a gear on the said housing, a ear on the motor shaft meshing therewith, and means operated through centrifugal force caused by rotation of the gear and housing to release the rod and lever to permit normal operation of the inlet, valve, said centrifugally operated device being adapted when idle or operating below a predetermined speed to cause movement of the lever to open the inlet valve against the tension of the valve s ring.

5. A mechanica unloading device for fluid compressors comprising the combina tion with a compressor having a spring closed inlet valve, an electric motor for operating the compressor, a lever pivotally mounted upon the compressor head and having one end engaging the valve stem, a reciprocable rod connected with the opposite end of the lever, a centrally apertured housing in which the rod ismovable longitudinally, a gear on the said housing, a gear on the motor shaft meshing therewith, a pair of weighted levers ivotally supported on the housin gear, eac having an end extending beneat the end of the rod, a spring tending to'draw the weighted levers together forcing the rod longitudinally of the housing against the tension of the valve spring and normally holding the valve open, the tension of the spring predetermining the centrifugal force required to cause the said ends to swing outward permitting the valve to close by action of its spring.

In testimony whereof, we sign this specification.

CLARENCE M. HOLLEY. EARL P. OSWALD. 

